Ammonia (NH3) is a colorless, corrosive, pungent gas used in a variety of industries including pharmaceutical, fertilizer, food, chemical, and semiconductor. It has an explosive range in air from 16-25% by volume and is moderately toxic. It has an Immediately Dangerous to Life and Health (IDLH) concentration of 300 ppmv with OSHA Permissible Exposure Limit (PEL) of 50 ppmv. The odor threshold for Ammonia is 5 ppmv, giving ample olfactory warning of potential danger. Although Ammonia is not a Hazardous Air Pollutant (HAP), it is regulated as a precursor to PM2.5 and PM10 Criteria Air Pollutants. This is because it reacts with acid gas pollutants to form respective Ammonium Salts in the atmosphere (such as Ammonium Sulfate or Ammonium Nitrate).

Aqueous Ammonia solutions have very high vapor pressure, which prevents plain water from being recycled in an air scrubber. The water must be discarded after a single pass through the air scrubber. In some instances, this may be acceptable or even desirable if the plant has a use for a solution of dilute Ammonium Hydroxide, i.e., Aqua-Ammonia. Due to the alkalinity of NH3, it is very effectively scrubbed using an acid solution. This allows recycle of the water due to the NH3 reacting to form a non-volatile Ammonium Salt. The most common acid used in air scrubbers is Sulfuric Acid, due to its availability, low cost and non-volatility. The product formed when Ammonia is scrubbed with Sulfuric Acid is Ammonium Sulfate, which is a common fertilizer ingredient. Thus, depending on the quantity of NH3 being scrubbed, the Ammonium Sulfate by-product may have market value. Ammonia air scrubbers incorporate a variety of gas-liquid contacting techniques, including packed beds, spray chambers and water jets. In every application, AAT, Inc. considers all factors in selecting the optimum design. We offer complete packages, including instrumentation and controls, skid-mounting of equipment, acid storage tanks and metering pumps, and installation.